Difference between BALANCED and UNBALANCED trim CONTROL VALVE

A pressure-balanced trim uses the process pressure to balance the static pressure acting on it, while unbalanced trim takes the full force of the process fluid.
Unbalanced trim: There is no balance hole on the plug, the medium pressure differential acts on the effective area of the plug to generate a force equal to the product of the differential pressure across the plug and the plug’s area (F = PA). However, balanced plugs do not generate this same force because they equalize the pressure on both sides of the plug.
Unbalanced trim control valves are suitable for applications where the pressure difference is not large.
Balanced trim control valves are suitable for applications with large pressure differences.
You can learn more about these in the below technical paper by Valtek
pro-quip.com/images/proquip/P...
Unbalanced trim design generally requires that the direction of flow should assist the motion of failure, for example, flow-over for fail-closed and flow-under for fail open.
Pressure-balanced trim design generally requires that the direction of flow be opposite to standard (unbalanced) trim to oppose the motion of failure for example, flow-over for fail-open and flow-under for fail-closed

[@AsadPassionateEngineer]

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[@divyeshjain56]

Also in slurry application you must avoid a balanced trim design as it might get choked and also possible to dislocation of valve stem

[@mohanramgunasundaram1568]

It’s it good we are getting videos on non Saturdays 🎉

[@AsadPassionateEngineer]

Most welcome, so glad to know you are finding these efforts valuable!!! 😊

[@balajiarni]

Good Content. Had a feel of spent valuable time by watching this video. Video Sound are clear

[@AsadPassionateEngineer]

Thank you so much Balaji, your comments really motivate me to work 10 fold more to produce such videos
I really appreciate you taking out the time to watch these videos !! 😊
Please also let me know i there are some specific topics you would love to see videos on. I will specially work on those !!

[@swaminnathan1]

Excellent refresher....

[@AsadPassionateEngineer]

thank you so much 😊 glad you liked it !!

[@milindketkar9059]

Normally we used pressure balanced trim when DP actuator was very high. Quite often very low pressure drop and large flow of say steam makes it difficult for an actuator to shut fully tight. Solution is pressure balanced trim or else use of electrical or hydraulic actuator instead of pneumatic actuator. Typical application are turbine bypass PRDS and spray water control valve with very low DP but very high inlet line water pressure.

[@AsadPassionateEngineer]

Thanks for such an insightful comment ..... and sharing your knowledge Milind !! 😊

[@cck1496]

Thanks. Would you kindly elaborate "how low pressure drop and high flow steam makes it difficult for actuator to shut fully tight".... Thanks.

[@ankurbhatnagar3241]

Nice one Asad

[@AsadPassionateEngineer]

Thanks a lot Ankur !!

[@saquibkhan1230]

Please make a video control valve seat leakage calculation.

[@AsadPassionateEngineer]

As requested the video is ready Saquib. Here is the Link to the Video : th-cam.com/video/j7Ew0JYoMpo/w-d-xo.html

[@instrumentwave5720]

Excellent.

[@AsadPassionateEngineer]

Thank you so much !!! 😊

[@prafuldethe3489]

Is there chances of leakage in stem side in case of balanced trim as pressure will also be acting upwards.

[@mohammednizamuddin5613]

May I know the high dp range?

[@manumani903]

My vendor used a blanced trim for a dp actuator sizing in 10bar and dp at max flow is 0.7 .is this is correct? Or to use unbalanced trim

[@balajiarni]

Again Saturday video, is that we can say DIWALI DAMAKA

[@anand9152]

❤

[@AsadPassionateEngineer]

Thank you anand 😊

[@cck1496]

Good video. What is the purpose of "cage" in the valve?
Thanks.

[@AsadPassionateEngineer]

I am planning a separate video that cover the difference between plug guide and cage guided . I hope that would help to answer your question

[@cck1496]

@@AsadPassionateEngineer Thanks, eagerly waiting for that.